Evaluation Report. Sixteen Slice CT Scanner Comparison Report Version (Free to the NHS) ImPACT report. MDA Evaluation Report MDA 03021

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1 February 2003 Evaluation Report NUMBER MDA Sixteen Slice CT Scanner Comparison Report Version 8 ImPACT report MDA Evaluation Report MDA Crown Copyright 100 (Free to the NHS)

2 WHAT YOU CAN EXPECT FROM MDA EVALUATION REPORTS The Device Evaluation Service (DES) aims to provide independent and objective evaluations of medical devices available on the UK market. Specialist centres, mainly in NHS Trusts, do the evaluations under long-term contract to, and in accordance with protocols approved by, the MDA. The evaluations are usually of a unit supplied by the manufacturer. We would expect this unit to be representative of the product on the market but cannot guarantee this. Prospective purchasers should satisfy themselves with respect to any modifications that might be made to the product type after MDA s evaluation. The reports are intended to supplement, not replace, information already available to prospective purchasers. Crown Copyright 2003 Apart from any fair dealing for the purposes of research or private study, or criticism, or review, as permitted under the Copyright, Designs & Patents Act, 1988, this publication may only be reproduced, stored or transmitted in any form or by any means with the prior permission, in writing, of the Controller of Her Majesty's Stationery Office (HMSO). Enquiries concerning reproduction outside those terms should be sent to HMSO at the undermentioned address: The Copyright Unit, The Stationery Office, St Clements House, 2 - Colegate, NORWICH, NR3 1BQ

3 ImPACT Imaging Performance Assessment of CT Scanners Sixteen Slice CT Scanner Comparison Report Version 8, February 2003 Manufacturer GE Philips Scanner model LightSpeed Advantage Mx8000 Somatom Sensation Multi Compiled and prepared by members of the ImPACT group , Crown Copyright

4 Table of contents TABLE OF CONTENTS...2 INTRODUCTION...3 Purpose of this report... 3 Comparison method... 3 Scanner performance... 3 Specification comparison... 3 Scanners covered in this report... 4 SCANNER PERFORMANCE...5 Introduction... 5 Dose efficiency... 6 Head scanning... 6 Body scanning... 6 Spatial resolution... 7 Limiting resolution... 7 Geometric efficiency... 8 Clinical scan tables... 9 Standard brain... 9 Standard abdomen... 9 Helical abdomen... 9 Inner ear... 9 High resolution spine SPECIFICATION COMPARISON...11 Scanner gantry Patient couch X-ray generator X-ray tube Detection system System start-up and calibration Scan parameters Helical scanning Scan Projection Radiograph (SPR)... Manufacturers performance data Factors affecting image quality Operator s console Main computer Image storage Image reconstruction D reconstruction Optional features Installation requirements...25 Independent workstation Image transfer and connectivity APPENDIX 1: IMAGE QUALITY ASSESSMENT AND Q...28 APPENDIX 2: IMPACT AND THE MDA...29 Background ImPACT ImPACT and MDA support to purchasers and users ImPACT Sixteen Slice CT Scanner Comparison Report v 8

5 Introduction Purpose of this report In January 2000, the UK government announced the funding for the replacement, over a three-year period, of all non-helical CT scanners in use in England. ImPACT produced comparison reports for the seven phases of the purchase program. The primary aim of these reports was to aid the equipment selection process by providing comparisons of CT scanners that are currently on the market. The previous set of Blue Cover comparison reports generally available was from Phase 7 of the government purchase, in August 2002 (report numbers MDA (single slice), (dual), (four slice) and (eight and sixteen slice)). Version 8 of report was produced to reflect changes in scanners since that date, and in anticipation of the availability of further funds for CT scanner purchase within the NHS. The scope of this report is limited to CT scanners that are capable of acquiring sixteen sets of attenuation data per tube rotation. Separate reports are available for single, dual, four and six to ten slice scanners. Comparison method The data given in this report are representative of the scanners as of February 2003, and are liable to change as the performance of individual scanner models is changed and upgraded. In particular, optional features such as workstations and software packages may be listed as standard for the scanner replacement programme, but may not be included in other, separate scanner purchases. There are two main areas for comparison of the scanners, performance and specification. Scanner performance This section presents the results of ImPACT s imaging and dose performance assessment of each of the scanners. Although manufacturers generally publish image and dose characteristics of their scanners, different measurement techniques and phantoms often make it very difficult to compare results from one scanner against another. The ImPACT performance assessments utilise standard techniques, and allow a fair, like-with-like comparison. Specification comparison The specification comparison is presented as a side-by-side summary comparison of the specification of each scanner, workstation and related equipment. It is grouped into a series of sub-sections relating to different aspects of the scanner, such as gantry, tube and detectors etc. ImPACT Sixteen Slice CT Scanner Comparison Report v 8 3

6 Introduction Scanners covered in this report At the time of writing, there are five manufacturers of medical CT scanners; (in alphabetical order) GE Medical Systems, Philips Medical Systems, Shimadzu, AG and Toshiba Medical Systems. Of these, GE, Philips, and Toshiba currently market sixteen slice scanners. The models are listed below. Manufacturer Scanner model GE LightSpeed Advantage Philips Mx8000 Somatom Sensation Multi The GE LightSpeed Advantage is based upon the LightSpeed series of scanners, but features a modified detector layout, consisting of sixteen 0.63 mm detectors banks and eight 1.25 mm detector banks. Reconstruction techniques on this scanner are modified from other LightSpeed models, and feature GE s MDMP algorithm. The is an upgraded version of the Mx8000 four slice scanner, which was previously produced by Marconi, until Philips acquired Marconi in November Its detector design is the same as on the Sensation, with sixteen 0.75 mm rows, and eight 1.5 mm rows. It features Philips Cobra cone beam reconstruction techniques, and a 0.42 second scan time is available for cardiac scanning. The Somatom Sensation is an upgraded version of the existing Somatom Sensation 4 (formerly Volume Zoom). Its detector design is the same as on the Philips Mx8000, with sixteen 0.75 mm rows, and eight 1.5 mm rows. It uses new AMPR image reconstruction techniques, and has a fastest scan time of 0.42 seconds for cardiac scanning. The Multi is a development of the four slice Multi scanner. The main difference between these scanners lies in the detector, which has sixteen 0.5 mm detector banks on the Multi, and four 0.5 mm detector banks on the Multi. The remainder of the 32 mm z-axis coverage of the detector consists of 1 mm banks on both scanners. In addition, on the Multi, Toshiba use a modified Feldkamp reconstruction algorithm, that they call TCOT. ImPACT has assessed the imaging and dosimetry of the GE LightSpeed and Sensation, and plan to assess the other scanners as soon as possible 4 ImPACT Sixteen Slice CT Scanner Comparison Report v 8

7 Scanner performance Introduction In order to compare the performance of CT scanners, the ImPACT evaluation programme has developed a range of assessment techniques. These were described in detail in MDA/98/25, Type Testing of CT Scanners: Methods and Methodology for Assessing Imaging Performance and Dosimetry. The results of this testing are presented in this section, which consists of data regarding different aspects of scanner performance. The dose efficiency section looks at the overall image quality of the scanner relative to the radiation dose delivered to the patient, for both head and body scanning. This is presented in terms of the ImPACT Q value. Spatial resolution compares the ability of the scanners to reproduce fine detail within an image, usually referred to as the high contrast spatial resolution This is presented as the 50% and 10% MTF values (known as MTF 50 and MTF 10 ) for the limiting clinical resolution of the scanner. Geometric efficiency examines the z-axis dose utilisation of the scanners. This is expressed as the ratio of the imaged slice thickness to the x-ray beam thickness. In general, scanners with a high geometric efficiency will not produce large patient doses, particularly for narrow slice thicknesses, where geometric efficiencies are normally lowest. Clinical scan tables lists the measured image quality and dose parameters for the standard ImPACT clinical scans. ImPACT Sixteen Slice CT Scanner Comparison v 8 5

8 Scanner performance Dose efficiency Dose efficiency is a term used to describe the quality of a scanner's images relative to the radiation dose to the patient. It can be expressed in a number of ways. ImPACT normally use the 'Q-value', which combines measurements of noise, high contrast resolution, slice thickness and dose to produce an imaging figure of merit (see Appendix 2 for more details). The Q 2 values presented in this section are for head and body imaging. The imaging parameters used for these scans are chosen to minimise slight variations that occur for different kv, slice thicknesses, scan times and reconstruction algorithm, by using standard values where possible: kv: 120 kv or 130 kv when this is the standard operating kv for the scanner. Slice thickness: 4 x 5 mm for head, 2 x 10mm for body, or the closest available setting. Scan time: 1.5 or 2 s for head, 1s or faster for body. Reconstruction algorithm: the algorithm chosen for each scanner is the one that most closely matches the average standard head and body algorithm (MTF 50 of 3.4 c/cm, MTF 10 of 6.0 c/cm). Reconstruction field of view: 250 mm (head) and 380 mm (body). The mas setting that would result in a CTDI w of 50mGy for head and 15mGy for body scanning is listed. Z-sensitivity, image noise at 50 or 15 mgy and MTF values are also shown. Head scanning Scanner Recon filter mas for 50mGy z-sens (mm) Noise (%) MTF 50 (c/cm) MTF 10 (c/cm) GE LightSpeed Soft Sensation H Q 2 Body scanning Scanner Recon filter mas for 15mGy z-sens (mm) Noise (%) MTF 50 (c/cm) MTF 10 (c/cm) Sensation B GE LightSpeed Soft Q 2 6 ImPACT Sixteen Slice CT Scanner Comparison Report v 8

9 Scanner performance Spatial resolution The spatial resolution figures given below show the capabilities of the scanners to reproduce fine detail within an image. Limiting resolution looks at the highest spatial resolution that can be achieved with the scanner, using a clinical reconstruction algorithm. Limiting resolution Scanner Recon MTF 50 MTF 10 filter (c/cm) (c/cm) Sensation U GE LightSpeed Edge The scan parameters used for the limiting resolution result are those that produce the highest spatial resolution i.e. fine focal spot, long (>1 s) scan time, sharpest reconstruction algorithm and small reconstruction field of view. ImPACT Sixteen Slice CT Scanner Comparison v 8 7

10 Scanner performance Geometric efficiency Geometric efficiency is a measure of the scanners dose utilisation in the z-axis. This is expressed as the ratio of the axial imaged slice section thickness relative to the z-axis dose profile. For optimum imaging, the geometric efficiency should be 1, but it is often less, especially for narrow beam collimations where post-patient collimation may be necessary to bring the imaged slice thickness closer to the nominal value. Geometric efficiency values of greater than 1 are due to the accuracy limits of the measurements. The data is presented in the form of a table and a graph. The table gives geometric efficiency values both for the setting closest to 1 mm slice thickness and also, where applicable, for the slice narrower than 1 mm. The graph presents data for all slice widths, showing how geometric efficiency varies with nominal imaged slice width. The total z- sensitivity figure is measured using fused slices. Error bars on the graph reflect the accuracy of measurements of the section thickness (± 0.2 mm) and dose profiles (± 0.2 mm). Scanner Slice thickness (mm) z- sensitivity (mm) Dose profile (mm) Total z- sensitivity (mm) Geometric efficiency GE LightSpeed x Sensation 12 x GE LightSpeed x Sensation 12 x Geometric Efficiency LS 2 and 4 slice LS slice S 2 slice S 12 slice Nominal Imaged Width (mm) Note: The LS 2 and 4 slice data for the LightSpeed is for two 0.63 mm slices and four 1.25 and 3.75 mm slices per rotation. 8 ImPACT Sixteen Slice CT Scanner Comparison Report v 8

11 Scanner performance Clinical scan tables These are a sub-set of the standard ImPACT clinical scan tables for a range of examination types. It should be noted that the exposure parameters listed were those suggested by the manufacturer, but in practice they will vary from site to site. In particular, the settings for ma and scan time, which define patient dose, may vary widely from one centre to another. Note that where the slice thickness is listed as being, for example, 4 x 5 mm, it will generally be acquired as 8 x 2.5 mm, and subsequently reconstructed to the wider slice width. Standard brain Head scan reconstructed to show low contrast brain detail. Scanner kvp mas Scan Slice FOV Recon CTDI W z-sens. Noise MTF 50 MTF 10 time (s) (mm) (mm) filter (mgy) (mm) (%) (c/cm) (c/cm) GE LightSpeed x Soft Sensation x H MEAN Standard abdomen Axial abdomen scan. Scanner kvp mas Scan Slice FOV Recon CTDI W z-sens. Noise MTF 50 MTF 10 time (s) (mm) (mm) filter (mgy) (mm) (%) (c/cm) (c/cm) GE LightSpeed x Std Sensation x B MEAN Helical abdomen Helical abdomen scan. Scanner kvp mas Scan Slice Pitch Recon CTDI W z-sens. Noise MTF 50 MTF 10 time (s) (mm) filter (mgy) (mm) (%) (c/cm) (c/cm) GE LightSpeed Std Sensation B MEAN Inner ear High contrast inner ear exam, using a narrow slice for good resolution in the z-axis. Scanner kvp mas Scan Slice FOV Recon CTDI W z-sens. Noise MTF 50 MTF 10 time (s) (mm) (mm) filter (mgy) (mm) (%) (c/cm) (c/cm) GE LightSpeed x Bone Sensation x U MEAN ImPACT Sixteen Slice CT Scanner Comparison v 8 9

12 Scanner performance High resolution spine High contrast spine examination. Scanner kvp mas Scan Slice FOV Recon CTDI W z-sens. Noise MTF 50 MTF 10 time (s) (mm) (mm) filter (mgy) (mm) (%) (c/cm) (c/cm) GE LightSpeed x Bone Sensation x B MEAN ImPACT Sixteen Slice CT Scanner Comparison Report v 8

13 Specification comparison Scanner gantry GE LightSpeed Sensation Generation 3rd 3rd 3rd 3rd Slipring Low voltage Low voltage Low voltage Low voltage Aperture (cm) Scan fields of view (cm) 25 and and , 24, 32, 40, 50 Nominal slice widths for axial scans (mm) * = Optional 0.625, 1.25, 2.5, 3.75, 5, 7.5, , 1.5, 3, 6, , 0.75, 1.0, 1.5, 3, 4.5, 5, 6, 9, , 1, 2, 3, 4 and summed images Tilt range (degrees) ± 30 ± 30 ± 30 ± 30 Type of positioning lights Laser Laser Laser Laser Accuracy of positioning lights (mm) ± 1 mm at any laser to patient distance ± 0.5 mm at centre of gantry ± 2 mm ± 1 mm ImPACT Sixteen Slice CT Scanner Comparison v 8 11

14 Specification comparison Patient couch Couch Top GE LightSpeed Sensation Material Carbon fibre Carbon fibre carbon fibre Carbon fibre Length and width (cm) 239 x 62 (or 42 just for cradle) 243 x x 40 (just for cradle) 200 x 47 Horizontal Movement Horizontal movement range (cm) Horizontal movement speeds (mm/sec) up to or 100 Accuracy/reproducibility of table positioning (mm) ± 0.25 ± 0.25 ± 0.5 ± 0.25 Scannable horizontal range (cm): (i) without table top extension (ii) with table top extension(s) Vertical Movement Vertical movement range out of gantry (cm) Vertical movement range in gantry (cm) Minimum couch top height outside gantry (cm) Weight Bearing Properties Maximum weight allowed on couch (kg) Maximum weight on couch which still achieves stated performance specifications (kg) 170 (Axial), 0 (Helical & Scout) 170 (Axial), 0 (Helical & Scout) (±0.25mm) 205 (±1mm) X-ray generator GE LightSpeed Sensation Type High frequency High frequency High frequency High frequency Location Rotation assembly Rotation assembly Rotation assembly Rotation assembly Power rating (kw) kv settings available 80, 100, 120, , 120, , 120, , 100, 120, 135 ma Range and Step size Max. ma allowed for each kv (5mA steps) 80kV: 400mA 100kV: 420mA 120kV: 440mA 140kV: 380mA (1mA steps) 90kV: 500mA 120kV: 500mA 140kV: 425mA (1mA steps) 80 kv: 375mA 120kV: 500mA 140kV: 428mA (10mA steps) kV: 500mA 135kV: 440mA 12 ImPACT Sixteen Slice CT Scanner Comparison Report v 8

15 X-ray tube GE LightSpeed Type and make GE Performix Marconi DFS Focal spot size(s) (mm), quoted to IEC 336/93 standard Total filtration (inherent + beam shaping filter) at central axis (mm Al equivalent) 0.6 x x (70kV, head) 5.65 (70kV, body) 0.5 x 0.7, 0.8 x 1.2 > 5.5 Anode heat capacity (MHU) Maximum anode cooling rate (khu/min) Specification comparison Sensation Dura Akron-Q 0.5 x 0.7, 0.8 x mm PTFE + 0.6mmTi (head), 2 mm PTFE + 1.2mmTi (body) 5.3 (run at 80% of full loading) Toshiba Megacool 0.9 x x 1.4 > 1 (inh) ,386 Method of cooling Oil to air Oil to air Oil to air Oil/forced air Guaranteed tube life One year (unlimited rotations) 200,000 revolutions 0,000 seconds of scanning (320,000 revolutions at 0.5s scanning) 200,000 rotations Detection system Detector type Number of detectors per row GE LightSpeed Solid state (HiLight / Lumex) 888 (plus 18 reference elements) Solid state (High speed ceramic) 690 Sensation Solid state (Ultra Fast Ceramic) 672 (1344 channels per row) Solid state 896 (plus 1 pair ref detectors) Number of elements along z-axis Effective length of each element at isocentre (mm) Total effective length of detector array at isocentre (mm) Future option for more slices / rotation x0.625, 8x1.25 x 0.75, 8 x 1.5 x 0.75, 8 x 1.5 x 0.5, 24 x None currently 32/64 slices WIP. None currently 256 row detector ImPACT Sixteen Slice CT Scanner Comparison v 8 13

16 Specification comparison System start-up and calibration Power-on to warm-up time (mins) Tube warm-up time from 'cold' to operating temperature (mins) Time to perform detector calibrations at warm-up (mins) Recommended frequency for any additional calibration by the radiographer Time to perform these additional calibrations (mins) Total time from fully off to scanning in an emergency (mins) GE LightSpeed 2 from fully off, 0 from standby 5 from fully off, approx. 2 from standby Sensation 45 secs Included in 45s tube warm-up Once every 24 hours Part of warm up procedure 8 2 from fully off, 0 from standby 2 (0 in an emergency) / 3 weeks Not required 1 per week 20 2 Not required Up to 20 < (11 with warm up) 2 Scan parameters GE LightSpeed Reconstruction fields of view (cm) 9.6 to 50 Nominal slice widths (mm) and number of simultaneous slices (axial scans) * = Optional Scan times for axial scans (s) * = Partial scans 2x0.625, 4x3.75, x0.625, 8x1.25, x1.25, 8x *, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4 (360 rotation) (0.1 steps) x 0.75, x 1.5, 8 x 3 0.3*, 0.42(option), 0.5, 0.75, 1, 1.5, 2 Sensation x 0.75, 12 x x 0.5, x 1, 1.5 ( for x2, 8 x 3, 8 x 4, perfusion) Smaller and summed numbers of wider images slices 0.33*, 0.42 (HeartView opt), 0.5, 0.75, 1.0, *, 0.5, 0.75, 1, 1.5, 2, 3 kv settings available 80, 100, 120, , 120, , 120, , 100, 120, 135 ma Range and Step size Max. ma allowed for each kv (5mA steps) 80kV: 400mA 100kV: 420mA 120kV: 440mA 140kV: 380mA (1mA steps) 90kV: 500mA 120kV: 500mA 140kV: 425mA (10mA steps) 80 kv: 375mA 120kV: 500mA 140kV: 428mA (10mA steps) kv: 500mA 135kV: 440mA 14 ImPACT Sixteen Slice CT Scanner Comparison Report v 8

17 Specification comparison Helical scanning GE LightSpeed Sensation Rotation times for helical scanning (s) Number of simultaneous slices at each rotation time Pitches available for routine scanning (range and increment) Recommended pitches for optimal image quality Helical interpolation algorithms available Maximum number of rotations in one helical run at standard abdomen parameters 0.5, 0.6, 0.7, 0.8, 0.9, (option), 0.5, 0.75, 1, (with HeartView option), 0.5, 0.75, 1, , 0.75, 1, slices: 0.625, 0.875, 1.35 and slices: , , and slices: 0.625, 0.875, 1.35 and slices: , , and 1.75 GE Proprietary algorithms (SmartHelical & MDMP, including CrossBeam TM & Hyperplane TM ) 1 (300mA) 150 (270mA) 183 (250mA) all at 0.6 s (4-24) freely selectable Any pitch may be used to optimise dose vs image quality Cobra - Cone Beam Reconstruction (8-24), freely selectable (8-24), freely selectable SureView TM 200 (300mA,.5s) 133 (200mA,.75s) 100 (150mA, 1s) 66 (100mA, 1.5s) 1 to to 1.5 MUSCOT and cone beam helical 120 (300mA) 200 (180mA) all at 0.5 s Maximum continuous scan time (s) Starting with a cold tube, the maximum helical scan distance using a 1 mm imaged slice thickness and a pitch of 1.5 Gantry tilt range for helical scanning (degrees) 00 mm 3600 mm (table limit 1800 mm) 1570 mm (limited by table) 1800mm ± 30 ± 30 ± 30 ± 30 ImPACT Sixteen Slice CT Scanner Comparison v 8 15

18 Specification comparison Scan Projection Radiograph (SPR) GE LightSpeed Sensation Maximum SPR length (mm) SPR field dimensions (mm x mm) 500 x 00 Angular positions of X-ray tube available for SPR Real time image Accuracy of slice prescription from the scanogram (mm) any angle from (1 steps) Yes width: 500 length: (1 mm steps) 0, 90, 180, 270 Available next s.w. release 512 x 1024 AP, PA, LAT (oblique in 10º steps) Yes width: 240, 400, 500, length: 200-1,390 0, 90, 180, 270 (oblique in 5º steps) Yes ± 0.25 ± 0.5 ± 0.5 ± 0.25 Accuracy of distance measurements from SPR's taken at isocentre (lateral and axial directions) (mm) < 2 x image pixel size ± 0.25 ± 0.5 < ± 0.5 ImPACT Sixteen Slice CT Scanner Comparison Report v 8

19 Specification comparison Manufacturers performance data Image Quality Spatial resolution (lp/cm) for sharpest clinical algorithm Contrast resolution: smallest rod size (mm) discernable at given parameters in 20 cm CATPHAN GE LightSpeed 0% MTF: 15.4 lp/cm 10% MTF : 13.0 lp/cm (10cm DFOV, Edge alg, Small Focus) mgy: 120 kv, 100 mas, 10 mm, 2i 1% MTF: 24 lp/cm (0.75 sec, 2.5 mm slice, 25 cm scan FOV, E-filter) 4 0.3% 120 kvp, 330 ma, 0.75 sec, 10 mm slice, 25 cm DFOV, EB filter, 27 mgy at center of phantom Sensation 0% MTF: 30lp/cm 0.75 s scan, U95u, 50mm FOV, small focus Spiral: mgy: 120 kv, 150 mas - std body, 2x10 mm 2% MTF: 14.5 lp/cm (120 kv, 200mA, 2 mm slice width, 1s, 180 mm FOV, FC90 algorithm, small focus) mgy: 120kV, 190 mas, FC41, 8 mm slice CT number accuracy Water : 0 ± 3 HU ±4 HU Air: ± 10 HU, water: Info. not available 0 ± 4HU Dose CTDI (mgy/100 mas) for axial standard brain scans at given 120kVp, 20 mm 120 kvp, 200mAs 120 kv, 20 mm 120kV, 20 mm parameters: 4 x 6 mm, - centre of CTDI phantom periphery of CTDI phantom CTDI (mgy/100mas) for axial standard abdomen scans 120 kvp 120 kvp, 200mAs 4 x 6 mm 120 kv, 20 mm 120 kv, 20 mm - centre of CTDI phantom periphery of CTDI phantom Dose profile FWHM (mm) (focal spot size in brackets) 20: 20.5(l) 15:.4 (l) 10: 11.7 (s) 2x0.63:1.9(s) ± 10% for all collimations. x 1.5: 27.0 (s), x 0.75: 14.7 (s) 32 : 35.9 (l) 20 : 23.2 (l) : 19.0 (l) 12 : 15.6 (s) 8 : 10.9 (s) 4 : 7.2 (s) 2 : 5.3 (s) ImPACT Sixteen Slice CT Scanner Comparison v 8 17

20 Specification comparison Factors affecting image quality GE LightSpeed Sensation Dose Post-patient collimation for narrow slices Automatic ma adjustment according to body dimensions or density during examination Noise Adaptive filtration for noise reduction No No No No SmartmA Doseright CARE Dose Low signal correction Adaptive image enhancement or smoothing for three density ranges Yes (automatic) Real EC (Exposure Control) Yes (user programmable) Resolution Quarter detector shift Yes Yes Yes Yes Moving (dynamic/flying) focal spot No Yes Yes No Number of imaging detectors per row (1344 channels) Sampling frequency 40 Hz Artefacts Artefact reduction algorithms Cone beam correction Iterative Bone Option (IBO), Motion correction Reconstruction of thick slices from thinner ones to reduce partial volume effects GE Proprietary algorithms (SmartHelical & MDMP, including CrossBeam TM & Hyperplane TM ) Iterative bone correction, COBRA cone beam reconstruction, combine slice Yes, cone beam reconstruction (COBRA) Modified beam hardening (abdomen, pelvis, shoulder), Motion correction (sequential modes), Posterior Fossa optimisation Yes, cone beam reconstruction (SureView) views/sec (0.5s scan), 1200 views/sec (>0.5s) Beam hardening correction, Raster Art. Suppression Protocol (RASP), stack scanning, automatic patient motion correction TCOT (True Cone Beam Tomography) Feldkamp method (modified) 18 ImPACT Sixteen Slice CT Scanner Comparison Report v 8

21 Specification comparison Operator s console Image Monitor Diagonal dimension of image screen (inches) GE LightSpeed Sensation (LCD) Number of monitors at console (functions of each if > 1) Image Display Image area matrix dimensions Usual range of CT Number displayed (HU) Accuracy of distance measurements in x-y plane (mm) Dose information 2 (patient info and technique selection / image display) 512 x 512, 768 x 768, 1024 x (patient set up 2 (acquisition/ and acquisition / review and review, recon and processing) filming) (shared database) to to < 2 times image pixel size 1024 x x 1024 ± 0.25 mm to (-10,240 to +30,710 if metal implants) depends on pixel size 2 (acquisition/ review and processing) 512 x 512, 512 x 1024, 1024 x to less than 1mm Weighted CTDI (CTDI W ) or CTDI vol displayed on console Dose Length Product (DLP) displayed on console Geometric Efficiency displayed on console when <70% Hardware Interface Control methods Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Mouse, trackball, keyboard Mouse, keyboard Mouse, keyboard Mouse, cursor, keyboard ImPACT Sixteen Slice CT Scanner Comparison v 8 19

22 Specification comparison Main computer GE LightSpeed Make and model HP XW4000 Dell Xeon Sensation PC compatible with array processors 2 x Silicon Graphics O 2 Operating system Linux Red Hat 7.3 Windows NT Windows NT IRIX Type and speed (MHz) of CPU 2 x 2.66 GHz CPU 3 x 2.2 GHz Intel Pentium IV 10 X 2.2 GHz (min) R1200, 300 MHz (scan console) + Octane 2, 400 MHz (display console) Amount of computer RAM (Mbytes): (i) supplied as standard (ii) maximum 12 GB ImPACT Sixteen Slice CT Scanner Comparison Report v 8

23 Specification comparison Image storage Hard Disk Storage GE LightSpeed Total standard hard disk capacity (Gbytes) Maximum hard disk capacity (Gbytes) Hard disk capacity for image storage (Gbytes and no. of uncompressed 512x512 images) Hard disk capacity for storage of raw data files (Gbytes and no. of data files) Archive options Archive options Capacity of a single archive disk (Gbytes and no. of images) Time to mount an archive disk or tape (s) Archive data transfer rate (images / s) Sensation (130,000 images) 72 (2800 slice 1 sec scans) MOD (standard) 4.6 (9400 losslessly compressed 512x512 images or 700 raw data files) 5-6 in background operation 1 (read) 0.7 (write) 146 (260,000 Images) 69 (15,000 data files) MOD and CD writer (standard) 9.1 (36,000 losslessly compressed 512x512 images. Factor 2-3 compression) Immediate (disk continually accessible) Less than 1s per image 73 (100,000 images) 150 (>100,000 data files) MOD and CD writer (standard) MOD: 4.1 (26,000 losslessly compressed images), CD-R: 0.65 (4800 compressed images) 256 x 256 matrix Approx. 30 for full disk 3600 rotations raw data and 60,000 image data double of standard 60,000 images 3600 rotations MOD 5.2 (19, x 512 images) less than 1 minute 2-3 background task ImPACT Sixteen Slice CT Scanner Comparison v 8 21

24 Specification comparison Image reconstruction GE LightSpeed Sensation Reconstruction matrix 512 x , 512, 768, , 512 Minimum reconstruction interval in helical scanning (mm) Reconstruction Times Time (s) from the start of data acquisition to the appearance of the 30th image of a series: (i) standard axial brain scan 55.8sec(with IBO) 11.3 Info. not available (ii) axial spine scan Info. not available (iii) helical abdomen scan Info. not available Parallel Processing Details Simultaneous scanning and reconstruction Yes Yes Yes Yes Any delay in either scanning or reconstruction when performed No No No No concurrently Simultaneous scanning and routine analysis Yes Yes Yes Yes Simultaneous scanning and archiving and/or hard copying Yes Yes Yes Yes Simultaneous scanning and transfer to second console/workstation Yes Yes Yes Yes 22 ImPACT Sixteen Slice CT Scanner Comparison Report v 8

25 Specification comparison 3D reconstruction 3D Reconstruction on Main Console (MC) and Workstation (WS) MIPs and MinIPs (maximum and minimum intensity projections) SSD (3D Shaded Surface Display) 3D Volume rendering software 3D Virtual endoscopy MPR (Multi-planar reconstruction) Planes available in MPR GE LightSpeed (MIP & MinIP) (3D) MC-N/A (Vol Rendering) (Navigator) (MPR & MPVR) Axial, para-axial, sagittal, coronal, oblique, curvilinear (Angio MIP) (3D SSD) (Vol Rend 4D Angio) (Vendo Voyager) (MPR) All planes, any oblique (identical on console and workstations) Sensation MC-option WS-option Axial, sagittal, coronal, oblique, curvilinear Axial, sagittal, coronal, oblique, curved with cross cut through the curved reformat ImPACT Sixteen Slice CT Scanner Comparison v 8 23

26 Specification comparison Optional features GE LightSpeed Sensation Contrast injector Optional Optional Optional Optional Contrast media bolus tracking CT fluoroscopy software and hardware Standard (SmartPrep) Optional (SmartStep) Standard (BolusPro Ultra) Optional (Continuous CT Imaging) Standard (CARE Bolus) Optional (CARE Vision with HandCARE) Standard Optional Hard-copy imaging device Optional Optional Optional Optional Radiotherapy Planning Accessories Radiotherapy planning table top Optional (RT flat pad and 'Exact' couch top) Optional (Exact table top) Optional Optional Carbon fibre breast board Optional Optional Optional N/A Means for attaching patient immobilisation devices and a stereotactic frame to the end of the couch Software Packages on Main Console (MC) and Workstation (WS) Bone Mineral Densitometry CT Angiography Dental Radiotherapy CT simulation software Prospective ECG-triggered cardiac software Retrospective ECG-gated cardiac software CT Perfusion software Optional (Exact couch) MC-N/A WS-optional (BMD), AVA (Vessel Assessment) on WS (optional) WS-optional (Dentascan) MC-N/A WS-optional (CT sim) WS-optional (SmartScore) (Cardiac Snapshot) ; MC+WS-optional (Cardiac Imaging) WS-optional (CT Perfusion) Optional Optional Optional WS-optional (Q BMAP II) (Angio MIP) WS-optional (DENT -3) WSoptional (AcQsim or SmartSim) WS-N/A (Prospective Gating) WS-optional (Retrospective Tagging) WSoptional (head + body perfusion) WS-Optional (Osteo CT) WS-optional (Dental CT) Available from 3rd party WS-optional (postprocessing only) (HeartView CS) WS-optional (postprocessing only) (HeartView CI) MC - optional, WS - optional (Perfusion CT) WS-N/A WS-optional WS-optional WS-N/A WS-N/A (Prospective Gating) Info. not available 24 ImPACT Sixteen Slice CT Scanner Comparison Report v 8

27 Specification comparison Installation requirements Environmental requirements (max/min temperature, humidity) in scanner room Environmental requirements (max/min temperature, humidity) in scanner control room Peak heat output from system during scanning (kw) GE LightSpeed ºC, 30-60% non-cond. rel. humidity ºC, 30-60% non-cond. rel. humidity 7.1 (75 rot/patient, 4 patient/hour) C, rel. humidity 40-60% C, rel. humidity 40-60% Sensation ºC, rel. humidity 15-75% ºC, rel. air humidity 15-75% ºC, rel. humidity 40-80% ºC, humidity 40-80% max System cooling method Output to air Water - air Water - water Output to air Air conditioning requirements for scanner room of minimum floor area Minimum floor area required for the system (m 2 ) Dimensions of: (i) Gantry (H x W x D (mm)) and weight (kg) (ii) Couch (H x W x L (mm)) and weight (kg) (iii) Supplementary units (H(mm)xW(mm)xD(mm)) and weight (kg) Power supply requirements Recommended Not required, other than for patient comfort None x 2230 x kg 1120 x 610 x kg Power Unit: 1270 x 762 x 585, 408kg 3 phase V, 90kVA 2050 x 2290 x 980, 2100 kg 480 x 670 x 2550, 500 kg Power unit: 1800 x 900 x 750, 550kg Cooling unit: 1800 x 900 x 750, 500kg 3 phase V, 90kVA 1990 x 2220 x 890, 2100 kg 850 x 680 x 2430, 500 kg Power unit: 1815 x 905 x 800, 550kg Cooling unit: 1815 x 905 x 860, 200kg 3 phase V, 66-83kVA Not necessary but recommended 25 (36 recommended) 1950 x 2320 x 960, 1750kg 390 x 620 x 2390, 330kg Transformer: 980 x 800 x 770, 550kg 3 phase V, 100kVA ImPACT Sixteen Slice CT Scanner Comparison v 8 25

28 Specification comparison Independent workstation Is a workstation provided? GE LightSpeed Standard Standard: MX VIEW Exp Computer make and model HP X4000 Dell Xeon Sensation Standard: LEONARDO Fujitsu Pentium 4 Standard: AlatoView Silicon Graphics O2 Operating system Linux Red Hat 7.3 Windows NT Windows NT Unix Type and speed (MHz) of CPU 2 x 2.2 GHz CPU 2.2 GHz Pentium (at least R12000, 300 MHz 1.7 GHz) Amount of computer RAM (Mbytes): (i) supplied as standard (min) 1024 (ii) maximum Total hard disk storage capacity (Gbytes): (i) supplied as standard 3 73 Minimum (ii) maximum 3 73 Currently Archive options Capacity of a single archive disk (Gbytes) Environmental requirements (max/min temperature, humidity) for workstation MOD (standard) 4.6 (9400 losslessly compressed 512x512 images or 700 raw data files) ºC, rel. noncond. humidity 20-80% at 40 ºC MOD (standard) CD-R (optional) 9.1 (36,000 losslessly compressed 512x512 images) 0-40 C CD-R (Standard), MOD (optional) MOD: 4.1 (26,000 losslessly compressed images), CD-R: 0.65 (4800 compressed images) 256 x 256 matrix ºC, rel. humidity 20-85% MOD (optional) 2.6 ( x 512 images - slightly compressed) ºC, rel. humidity 40-80% 26 ImPACT Sixteen Slice CT Scanner Comparison Report v 8

29 Specification comparison Image transfer and connectivity Speed of scanner / workstation connections to local area networks (Mbits/s) Remote PC access to images on workstation DICOM service classes provided by CT console (SCP and SCU) DICOM service classes provided by Independent workstation (SCP and SCU) GE LightSpeed Sensation Optional Storage SCU and SCP, Query/Retrieve, Media service class, Print (std.), Modality Worklist (opt.), Performed procedure step (opt) Optional (Easyweb) Storage SCU and SCP, query/retrieve, print, modality worklist Storage SCU and Storage SCU and SCP, SCP, Query/RetrieveSCU, query/retrieve and print, media interchange print Optional Storage SCU and SCP, query/retrieve, print, modality worklist (std), MPPS (Modality Performed Procedure Step) (opt) Storage SCU and SCP, query/retrieve, print Optional Storage SCU and Print (standard), Storage SCP and modality worklist (optional) Storage SCU and SCP, print, query/retrieve ImPACT Sixteen Slice CT Scanner Comparison v 8 27

30 Appendix 1: Image quality assessment and Q Statistical noise, spatial resolution and slice sensitivity are fundamental parameters describing the amount of object information retrievable from an image, or its image quality. X-ray dose can be regarded as a 'cost' of this information. In general, it is meaningless to quote any one of these measurements without reference to the others. The Q-value incorporates dose, noise, spatial resolution and slice width into one number. This figure is derived from a relationship between image quality and dose received. A dose efficiency factor has a fundamental meaning, in that a dose efficient scanner will produce good resolution at minimum dose and noise. However, it can take a number of forms depending on how the various parameters are measured and quoted. The Q-value used in this comparison report, Q 2, is the same one used in Comparison Report 12 (MDA/00/11), which was modified from the previous value used by ImPACT, Q 1. Q 2 is defined as follows: Q 2 = f av 2 σ z CTDI 1 3 w where: σ = image noise, expressed as a percentage for a 5cm 2 region of interest at the centre of the field of view in the standard ImPACT water phantoms. f av = spatial resolution, given as (MTF 50% + MTF 10% )/ 2 Where MTF 50% and MTF 10% are the spatial frequencies corresponding to the 50% and 10% modulation transfer function values respectively (in line pairs per cm). z 1 = the full width at half maximum (FWHM) of the imaged slice profile (z-sensitivity). This is measured using the inclined plates method for axial imaging, and using a 0.1mm thickness, 6mm diameter tungsten disc for helical scanning CTDI w = weighted CT dose index, as defined in EUR 262 The Q-factor is in part empirical and it should be used with caution. It is not an absolute figure, as its derivation relies on assumptions of the shape of convolution filter used. Comparisons between scanners will be more reliable when comparing scans reconstructed with similar convolution filters. It is of most importance when considering the standard scans for head or body. The uncertainty in this value is up to about +/-15%, with a conservative estimate of ±10%. 28 ImPACT Sixteen Slice CT Scanner Comparison Report v 8

31 Appendix 2: ImPACT and the MDA Background One of the roles of the Medical Devices Agency (MDA) is to fund evaluation programmes for medical devices and equipment. The programme includes evaluation of x-ray Computed Tomography Equipment currently available on the UK market. MDA aims to ensure that evaluation techniques keep abreast of improvements in CT imaging performance and that MDA reports present evaluation information that is timely, useful and readily understood. ImPACT ImPACT (Imaging Performance Assessment of Computed Tomography) is the MDA's CT evaluation facility. It is based at St George's Hospital, London, part of St George's Healthcare NHS Trust. ImPACT have developed test objects and measurement procedures suitable for intercomparing CT scanner performance. For each CT evaluation hundreds of images are obtained from the system under test and subsequently analysed using custom written software. Dose measurements are made using ion chambers, and x-ray film is used to obtain additional x-ray dose information. Members of ImPACT contributing to and writing this report: N. Keat, M. A. Lewis, J. F. Barrett and S. Edyvean (ImPACT Group Leader). ImPACT and MDA support to purchasers and users The ImPACT team is available to answer any queries with regard to the details of this report, and also to offer general technical and user advice on CT purchasing, acceptance testing and quality assurance. ImPACT Bence-Jones Offices St. George's Hospital London SW17 0QT Tel: Fax: web site: MDA contact point for general information on the CT evaluation programme: Arthur Goodman Programme Manager Room 1207, Hannibal House Elephant and Castle London SE1 6TQ Tel: Fax: ImPACT Sixteen Slice CT Scanner Comparison Report v 8 29

32 MEDICAL DEVICES AGENCY MDA Evaluation Reports MDA evaluation reports are published by the Medical Devices Agency, an Executive Agency of the Department of Health. They are available free of charge to the UK National Health Service (NHS), and are for sale to commercial organisations and other interested parties. A free catalogue of available reports can be obtained from the Orders Department, or downloaded from the MDA web site: Ordering Send your order to the address given below, stating the number, title and quantity of each report required. Your reports will be despatched by second class post the following working day. If you are not a representative of the NHS, you will be invoiced separately. Non-NHS customers are reminded that it is not possible to offer refunds for reports ordered in error. Enquiries Orders Department Room 1207 Medical Devices Agency Hannibal House Elephant and Castle London SE1 6TQ Tel: Fax: dep@medical-devices.gov.uk General publication enquiries should be directed to the Orders Department: Tel: Fax: dep@medical-devices.gov.uk

33 ISBN Smart number